The present invention relates to a coil assembly of a voice coil motor, arranged in opposed relation to permanent magnets and supplied with electric current to undergo movement.
The conventional coil assembly of a voice coil motor has structure as shown in FIGS. 3 and 4. Namely, the assembly has a coil frame 11 interposed in opposed relation to a pair of permanent magnets 18A and 18B which face with each other. A pair of coils 12A and 12B are wound on the coil frame 11. These coils 12A and 12B are supplied with electric current within magnetic field generated by the permanent magnets 18A and 18B so as to induce attractive or repulsive force effective to drive the coil frame 11. Such voice coil motor is used as a driving source.
Typical type of the above mentioned coil frame is formed by molding of plastic such as phenol resin in view of production cost. Such type of the coil assembly is utilized, for example, in an magnetic disc drive in which a magnetic head is floated on a magnetic disc with spacing of submicron order. When applying electric current to coils of the coil assembly in order to drive the magnetic head, an insulating layer of the coil, the coil frame or adhesive between the coil and coil frame is heated to generate a considerable amount of gas. The gas deposits on the magnetic disc and the magnetic head to thereby cause serious trouble so-called head clash to destroy the magnetic disc and head.